References of "Destain, Marie-France"
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See detailMeasurements Of The Horizontal Sprayer Boom Movements By Sensor Data Fusion
Ooms, David ULg; Lebeau, Frédéric ULg; Ruter, R. et al

in Computers and Electronics In Agriculture (2002), 33(2),

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See detailOn-line fruit grading according to their external quality using machine vision
Leemans, Vincent ULg; Magein, Hugo ULg; Destain, Marie-France ULg

in Biosystems Engineering (2002), 83(4), 397-404

This paper presents apple grading into four classes according to European standards. Two varieties were tested: Golden Delicious and Jonagold. The image database included more than a 1000 images of fruits ... [more ▼]

This paper presents apple grading into four classes according to European standards. Two varieties were tested: Golden Delicious and Jonagold. The image database included more than a 1000 images of fruits (528 Golden Delicious, 642 Jonagold) belonging to the three acceptable categories-Extra, I and II-and the reject (each class represents, respectively, about 60, 10 and 20% of the sample size). The image grading was achieved in six steps: image acquisition; ground colour classification; defect segmentation; calyx and stem recognition; defects characterisation and finally the fruit classification into quality classes. The proposed method for apple external quality grading showed correct classification rates of 78 and 72%, for Golden Delicious and Jonagold apples, respectively. Taking into account that the healthy fruit were far better graded and considering that this class was under represented in the sample compared with the fruit population, the results of the proposed method (an error rate which drops to 5 and 10%, respectively) are compatible with the requirements of European standards. (C) 2002 Silsoe Research Institute. Published by Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailSpray pattern simulation model for standardisation of boom behaviour tests.
Lebeau, Frédéric ULg; Bouchat, X.; Ruter, R. et al

in Aspects of Applied Biology (2002), (66),

Simulation models of spray pattern are required for the dynamic behaviour assessment of sprayer booms. The reasons are their ease of use and their independence regarding variable operating conditions such ... [more ▼]

Simulation models of spray pattern are required for the dynamic behaviour assessment of sprayer booms. The reasons are their ease of use and their independence regarding variable operating conditions such as liquid properties and nozzle state, which interfere with the discrimination between various dynamic behaviours properties. Although such models have been developed for many decades, no international consensus has been reached on their use in a standardised test procedure. A consensual model is tested in the scope of standardisation specific needs. It uses ISO-5682/1 spray table measurements of the static distributions to compute three 2-D distribution at three heights using a filtered back-projection algorithm. These distributions are interpolated to generate a 3-D matrix of repartition at various heights. This 3-D matrix is used as nozzle distribution description in a dynamic distribution model where the dynamic distribution is computed as a summation of the static distribution at successive positions. The model kernel was found suitable to predict the repartition under a moving boom. [less ▲]

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See detailApplication of image analysis to the identification and rating of road surface distress
Rasse, Catherine; Leemans, Vincent ULg; Destain, Marie-France ULg et al

in Correia; Branco (Eds.) Bearing Capacity of Roads, Railways and Airfields (2002)

Numerical image analysis is used to detect narrow cracks on bituminous pavement. This problem is complicated because of the variable road aspect, which depends on coarseness textures, changing ambient ... [more ▼]

Numerical image analysis is used to detect narrow cracks on bituminous pavement. This problem is complicated because of the variable road aspect, which depends on coarseness textures, changing ambient lighting, presence of humidity and because of the poor contrast of the cracks with regard to road texture. The paper presents algorithms suited to detect random cracks edges in a noisy environment in three stages. The pre-treatment consisted mainly in applying a background correction to eliminate the heterogeneity due to humidity, shade, ... In the treatment, a threshold value was applied to segment the 'object' from the rest of the image. As these objects may be cracks, part cracks, or some noise erroneously segmented as defect, a post-treatment was applied to appreciate more accurately if a pixel belonged to an object or to the background. It aimed also to assembly parts of the cracks in continuous structure. When compared to visual detection, efficient detection of cracks is obtained. Further work needs to be done to get an automatic detection of the cracks whatever the road texture. [less ▲]

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See detailSpray controller for horizontal boom movements compensation
El Bahir, Loussain; Lebeau, Frédéric ULg; Destain, Marie-France ULg et al

in Proceedings of AgEng2002 (2002)

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension ... [more ▼]

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles. Manufacturers classically try to reduce unwanted nozzles movements using horizontal boom suspension but these methods show performance and price limitations. The purpose of this paper is to propose a spray controller aiming to compensate the effect of the horizontal boom movements on the spray distribution besides the effect of tractor speed variations. The controller is based on three main parts: a control law describing the relationship between nozzle speed, nozzle flow and spray coverage; a real time measurement of the boom horizontal speed variations using micro-machined capacitive accelerometers and Pulse Width Modulation (PWM) no zzle flow actuators. A prototype was developed using a processor board controller (dSpace) and tested on a laboratory test bench. The nigrosine solution spray coverage was measured using image analysis for field representative multi-sine nozzle speed variations. The spray coverage uniformity using the spray controller showed about 51% compensation of the spray coverage variations observed without controller. [less ▲]

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See detailMapping within-field soil variability for precision agriculture using electromagnetic induction
Hanquet, Bernard; Frankinet, Marc; Parez, Vincent et al

in Proceedings of AgEng (2002)

Among the crops production factors, the soil is obviously one of the most important. Therefore, within the context of Precision Agriculture, the spatial variability knowledge of its physical and chemical ... [more ▼]

Among the crops production factors, the soil is obviously one of the most important. Therefore, within the context of Precision Agriculture, the spatial variability knowledge of its physical and chemical properties is essential as a decision support information for cultural operations modulation. The purpose of this study is to assess the capability of electromagnetic induction sensing of apparent electrical conductivity (ECa) for the characterisation of withinfield variability of soil physical and/or chemical properties in the particular soil conditions encountered in our experimental area, namely non-saline deep silty soils. ECa maps were produced on a 7ha field in April 2001, September 2001 and April 2002. Concurrently, an intensive soil survey (112 points) was carried out in February 2001 in order to determine a series of physical, textural and chemical soil parameters. ECa accurately described clay content, and exchangeable K and Ca cations concentrations. [less ▲]

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See detailDevelopment of a multibody model of a sprayer
Ooms, David ULg; Lebeau, Frédéric ULg; Maton, Nicolas et al

in Proceedings of AgEng (2002)

A multibody model of a sprayer boom including the suspension was developed by using ADAMS 11.0 (Mechanical Dynamics). The model was designed with the aim to describe the dynamic behaviour of different ... [more ▼]

A multibody model of a sprayer boom including the suspension was developed by using ADAMS 11.0 (Mechanical Dynamics). The model was designed with the aim to describe the dynamic behaviour of different types of booms and suspensions (double trapezium, trapezium, pendulum, …). This was obtained by creating a general model in which geometrical (dimensions) and mechanical parameters (mass and inertia, friction coefficients, stiffness and damping coefficients of the hinges, …) of the system were easily modified. A graphical interface especially designed authorised this easy modification. The validation of the model was obtained by measuring in real conditions the frame movements as solicitations and the boom movements as responses. The method was applied on a trailed sprayer equipped with a boom of 24 m and a trapezoidal suspension. Good accordance was found between measured and simulated vertical displacements. The model may decrease the development costs of suspension and boom designs. [less ▲]

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See detailEvaluation of tactile sensors in apple firmness measurement
Petit, Catherine; Leemans, Vincent ULg; Kleynen, Olivier et al

in Proceedings of the Conference 'Physical Methods in Agriculture, Appoach to precision and quality' (2001)

The objective of the work consists to develop a non-destructive fruit firmness measurement. The tactile sensor technology was chosen. The force measurement acting between the fruit-sensor as well as the ... [more ▼]

The objective of the work consists to develop a non-destructive fruit firmness measurement. The tactile sensor technology was chosen. The force measurement acting between the fruit-sensor as well as the contact area are coupled with other meaqsurements, like the color of the fruit. The results of the measurements are compared with the firmness reference values (Magness-Taylor test) and also with the acoustic impulse response technique. Several parameters correlated with firmness are proposed. [less ▲]

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See detailDéveloppement de méthodes pour apprécier 'en ligne' la qualité externe de pommes par vision artificielle
Leemans, Vincent ULg; Destain, Marie-France ULg; Magein, Hugo ULg

Book published by Ministère des Classes moyennes et de l'Agriculture - DG6 -Service Recherche subventionnée (2001)

L'ouvrage présente les résultats des recherches effectuées pour mettre au point un système de tri automatisé pour pommes, en fonction des critères de qualité externe, la couleur, la forme et la présence ... [more ▼]

L'ouvrage présente les résultats des recherches effectuées pour mettre au point un système de tri automatisé pour pommes, en fonction des critères de qualité externe, la couleur, la forme et la présence de défauts. [less ▲]

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See detailSensor Data Fusion for the Measurement of Horizontal Sprayer Boom Displacement
Lebeau, Frédéric ULg; Destain, Marie-France ULg

Conference (2000, September 14)

The measurement of horizontal sprayer boom movements is an important parameter for the simulation of repartition generated by a sprayer in the dynamic environment of agricultural fields. The existing ... [more ▼]

The measurement of horizontal sprayer boom movements is an important parameter for the simulation of repartition generated by a sprayer in the dynamic environment of agricultural fields. The existing methods were unsatisfactory for diverse reasons as limited measurement length or insufficient accuracy. Two different sensor data fusion methods were evaluated as input for a model aimed at predicting longitudinal spray deposit. A combination of radar and two accelerometers measurements was found more suited than laser and radar measurements combined in predicting spray repartition. [less ▲]

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See detailA Soil Mechanical Resistance Sensor For On-Line Application In Precision Agriculture: Soil Strength Mapping And Correlation With Soil Physical Properties
Sirjacobs, Damien ULg; Destain, Marie-France ULg

in Proceedings of the 15th Conference of the International Soil Research Organization (I.S.T.R.O.) (2000, July)

Knowledge of local soil strength variation may permit variation of tillage parameters to produce a more optimal soil structure for root growth and plant development. Soil strength mapping can provide ... [more ▼]

Knowledge of local soil strength variation may permit variation of tillage parameters to produce a more optimal soil structure for root growth and plant development. Soil strength mapping can provide another layer of information in precision agriculture. The aim of this research is to develop a sensor able to measure on-line the local soil strength variations. This sensor is designed as follows: a thin blade penetrates the soil to a specific depth while the machine is moving, a beam transfers the soil-blade forces to a transducer fixed on the machine. The transducer measures then the horizontal and vertical forces and the moment. This paper describes a field experiment performed in a 2 ha field of silt soil (Hesbaye, Belgium). The first objective of this research is to establish a map of soil strength variability of the field. For this purpose, the sensor is pulled through the soil in parallel traverses at 5 m separation by a tractor equiped with a DGPS receiver. The second objective of the experiment is to study relation between measured forces and several measured soil physical parameters. Ten homogeneous plots where identified on the sensor track in order to cover as completely as possible the diversity of soil physical conditions encountered. On the median line of each of those plots, 10 Cone Index penetrometry profiles were measured with a mobile automated penetrometer recorder, soil water content was measured in 5 points, ans soil samples were taken in the center of the plot to determine the following parameters: cohesion and internal friction angle, simple compression resistance, Atterberg's limits, granulometry and pF curves. This experiment allowed the first identification of different soil strength areas in the field investigated. [less ▲]

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See detailOn-line fruit grading according to external quality using machine vision.
Leemans, Vincent ULg; Magein, Hugo ULg; Destain, Marie-France ULg

in AgEng Warwick 2000 - Abstract part 1 - Agricultural engineering into the third millennium (2000, July)

This paper presents apple grading into four classes according to European standards. Two varieties were tested, the Golden delicious and the Jonagold. The image database included more than thousand images ... [more ▼]

This paper presents apple grading into four classes according to European standards. Two varieties were tested, the Golden delicious and the Jonagold. The image database included more than thousand images of fruits (528 Golden, 642 Jonagold) belonging to three categories Extra, I, II and to reject. The image grading was achieved in six steps : the image acquisition, the ground colour classification, the defect segmentation, the calyx and stem recognition, the defects characterisation and finally the fruit classification in quality classes. The proposed method for apple external quality grading showed correct classification rates of 78 and 72% respectively for Golden delicious and for Jonagold apples. Taking into account that the healthy fruits were far better graded and considering that this class was under represented, the results of the proposed method (an error rate reaching respectively 5 and 10%) are compatible with the requirements of the European standards. [less ▲]

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See detailLa résistance mécanique du sol: mesure en continu et cartographie pour l’agriculture de précision
Sirjacobs, Damien ULg; Destain, Marie-France ULg

in Zwaenepoel, Philippe (Ed.) Agriculture de Précision - Avancées de la recherche technologique et industrielle (2000, May)

La résistance mécanique d'un sol est un paramètre important qui conditionne la croissance racinaire et le développement des plantes. L'objectif de cette recherche est de mettre au point un capteur capable ... [more ▼]

La résistance mécanique d'un sol est un paramètre important qui conditionne la croissance racinaire et le développement des plantes. L'objectif de cette recherche est de mettre au point un capteur capable de mesurer en ligne les variations locales de résistance du sol. Celui-ci est constitué d'un anneau dynamométrique qui enregistre automatiquement les sollicitations (forces horizontales, verticales et couple) générées par la traction uniforme d'un lame dans le sol. Une première expérience a été menée dans un champ limoneux situé en Hesbaye (Belgique). Le géocodage de ces informations via un système DGPS a permis d'identifier des zones de diverses résistance au sein de la parcelle étudiée. [less ▲]

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See detailAutomatisation d'un banc de répartition pour buses de pulvérisation
Lebeau, Frédéric ULg; Hamza, Elies; Destain, Marie-France ULg

in Cahiers Agricultures (2000)

Les bancs de répartition constituent l'élement de base permettant de tester la sensibilité de la distribution transversale des buses de pulvérisation aux différents paramètres de fonctionnement. L'article ... [more ▼]

Les bancs de répartition constituent l'élement de base permettant de tester la sensibilité de la distribution transversale des buses de pulvérisation aux différents paramètres de fonctionnement. L'article présente un banc d'essai conforme à la norme ISO 5682/1 qui permet une lecture automatisée des différentes grandeurs (pression, débit, volume recueilli). [less ▲]

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See detailQuality fruit grading by colour machine vision: defect recognition.
Leemans, Vincent ULg; Destain, Marie-France ULg; Magein, Hugo ULg

in Acta Horticulturae (2000), (517), 405-412

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See detailDefect segmentation on 'Jonagold' apples using colour vision and a Bayesian classification method
Leemans, Vincent ULg; Magein, Hugo ULg; Destain, Marie-France ULg

in Computers & Electronics in Agriculture (1999), 23(1), 43-53

This paper shows how the information enclosed in a colour image of a bi-colour apple can be used to segment defects. A method to segment pixels, based on a Bayesian classification process, is proposed ... [more ▼]

This paper shows how the information enclosed in a colour image of a bi-colour apple can be used to segment defects. A method to segment pixels, based on a Bayesian classification process, is proposed. The colour frequency distributions of the healthy tissue and of the defects were used to estimate the probability distribution of each class. The results showed that most defects, namely bitter pit, fungi attack, scar tissue, frost damages, bruises, insect attack and scab, are segmented. However, russet was sometimes confused with the transition area between ground and blush colour. (C) 1999 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailLa vision artificielle et la qualité externe des produits agricoles et agro-alimentaires
Leemans, Vincent ULg; Destain, Marie-France ULg

in Application de systèmes optoélectroniques pour le contrôle en ligne des produits agroalimentaires (1998, June 03)

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See detailApplication of neural networks in quality control of 'Jonagold' apples
Leemans, Vincent ULg; Bieuvelet, Frédéric; Destain, Marie-France ULg

in Bellon-Maurel, Véronique (Ed.) Sensoral 98 - International workshop on sensing quality of agricultural products (1998, February)

This paper studies the possibilities to grade the 'Jonagold', a bicolour apple, using neural networks and Fisher"s linear discriminant analysis. In a first step the pixels are sorted into three areas, the ... [more ▼]

This paper studies the possibilities to grade the 'Jonagold', a bicolour apple, using neural networks and Fisher"s linear discriminant analysis. In a first step the pixels are sorted into three areas, the blush colour area, the intermediate colour area and the ground colour area; the accuracy reached 95% with the neural networks. Int the second step the fruit are graded into four categories on their ground colour basis; the accuracy reached 68%whatever the method used. It si also shown that there is no need to separate the ground colour and the intermediate colour to compute the ground colour classification parameters. [less ▲]

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See detailDefects segmentation on 'Golden Delicious' apples by using colour machine vision
Leemans, Vincent ULg; Magein, Hugo ULg; Destain, Marie-France ULg

in Computers & Electronics in Agriculture (1998), 20(2), 117-130

A method based on colour information is proposed to detect defects on 'Golden Delicious' apples. In a first step, a colour model based on the variability of the normal colour is described. To segment the ... [more ▼]

A method based on colour information is proposed to detect defects on 'Golden Delicious' apples. In a first step, a colour model based on the variability of the normal colour is described. To segment the defects, each pixel of ail apple image is compared with the model. If it matches the pixel, it is considered as belonging to healthy tissue, otherwise as a defect. Two other steps refine the segmentation, using either parameters computed on the whole fruit, or values computed locally. Some results are shown and discussed. The algorithm is able to segment a wide range of defects. (C) 1998 Elsevier Science B.V. All rights reserved. [less ▲]

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